Methods and means for continuous manufacturing of integral dripper lines (known also as in-line drip lines), with discrete flat drippers (drip irrigation emitters) integrated in them, are familiar and well known. For example, integrating the drippers and attaching them flush unto the inner wall might be formed during the process of manufacturing the hose (in other words—the conduit or hose), by extrusion (see for example U.S. Pat. No. 5,022,940 or IL patent No. 86549).
In order to maintain a beneficial competitive edge, manufacturing of integrated dripper lines in which discrete flat drippers are integrated mandates as high as practicable manufacturing rates. From its inception, the drippers have to be designed in such a manner that it would be possible to feed (insert) them in the hoses' production line at (very) high rates, while avoiding, as much as feasible—occurrences of mistakes in the feeding direction of the discrete flat drippers relative to the wall of the hose. In other words, designers of the drippers are required to design the drippers in a symmetric configuration, to the highest possible result, in order to reduce the impeding sorting operations—namely the requirements governing the preliminary adjustment and orientation of the dripper relative to the direction of the wall of the hose, even before they are attached flush to the inner wall of the hose, so that for example, it would be feasible forming the water outlet opening in the wall of the hose, accurately facing (opposite) the exit “pool” and within its boundaries.
The drippers have to be made in small dimensions—in order to save on the costs of the raw material that serve for their production (and—as well—to enable their speedy feeding (insertion) as said). The raw material, from which the dripper's components are manufactured, constitutes a dominant component of the cost of manufacturing of the integral dripper hoses.
In case of a non-pressure compensated dripper, the dripper is a mono-component (a single one), namely—the body component. In case of a ‘pressure compensated’ dripper, or in other words—‘flow rate regulated’ dripper. A typical dripper is made of usually three components, which are: a body member, a cover element and an elastomeric membrane (diaphragm) assembled between the body member and the cover element).
Hence, the designers of the drippers are required to decrease and reduce the dimensions (size) of the drippers as much as practicable (and thus achieve the savings in the costs of the materials and of other attending costs).
As opposed to this, in order to facilitate as much as practicable the task of conforming with the challenge of locating the water exit “pool” that is formed in the body of the dripper and accurately forming as well the water outlet openings in the wall of the hose into it and within its boundaries, the designers of the drippers strive to precisely increase and widen as much as possible, the surface area of that water exit “pool”.
Rather in the same manner, striving to filter as much as possible the water entering into the dripper (in order to prevent the formation or development of clogging up in the narrow passage of the pressure reducing mechanism in the dripper), this need also mandates assigning substantial area for increasing the area of the filtering means (and thus increasing the dripper's size). Similarly, striving to leave as large as possible minimal flow passage in the water pressure reducing means formed in the dripper (for example—the flow passage formed between the baffles of a water pressure reducing means of the labyrinth type), in order to prevent clogging, also leads to increase the dripper's size (and as per the example above, assigning a larger area to the labyrinth type water pressure reducing means enables to lengthen it, and this lengthening in its turn enables to increase the dimensions of the minimal flow passage in it).
An additional aspect which is critical in the realm of manufacturing integral dripper hoses with flat drippers integrated in them is the required assurance of properly affixing the body of the dripper unto the inner wall of the hose. Irrigating hoses might be manufactured in a (large) variety of inner diameters. In order to achieve reliable affixing of the body of the dripper unto the surface of the inner wall of the hose and because of the aforesaid large variety of actually manufactured different hoses, it is necessary to achieve suitability of the surface of the flat drippers that are adapted to be affixed flush unto the surface of the inner wall of the hose, to the outline of the surface of the inner wall of the hose (an outline that—in accordance to all the stipulations that were stated above might be different from one to another in accordance with the inner diameter of a specific hose). Hence, it is familiar and well known in this field—to form the surface of the flat drippers that are intended to be attached (affixed) flush to the inner wall of the hose, in an arched outline (in accordance with the inner radius of the hose). The variety of the diameters of the hoses might, hence, necessitate forming bodies of drippers with surface outlines in accordance with the specific radius of the inner wall of the hose unto which the drippers are designated to be affixed or alternatively, the designers of the drippers strive precisely to narrow, as much as possible, the dripper's width (in order that they will be properly affixed to a variety of inner diameters).
Integral dripper hoses might be buried in the ground (in order to ensure fast wetting of the ground and in order to prevent their moving in high winds). Burying the hose in the ground might worsen the problem of clogging from the instant that the water pressure drops in the hose and causes a phenomenon of sucking (suction) from the outside inwards of soil, sand, debris and the like. A familiar and well known solution is forming a water exit outlet at the wall of the hose in a configuration of an elongated thin slit (e.g.—formed by laser or sharp blade), such that as the water pressure drops inside the hose, it “closes” itself within the hose and prevents contaminating bodies from entering from the instant the sucking phenomena starts. This type of solution is known for applications of integral dripper hoses in which a continuous and flat strip of drippers is integrated (as different from a hose with discrete flat drippers within it). The configuration of the continuous strip enables forming a long water exit “pool” along the pressure reducing means, in a manner that enables forming the elongated and thin slit at the wall of the hose within its domain.
There exists a problem here—that in integrated dripper hoses with flat discrete drippers integrated in them (as different from integral irrigating hoses with a continuous strip of drippers), the water exit “pool” that is formed in each and every one of the discrete drippers, has to be of large enough dimensions, so that the water exit outlet (in the thin and elongated slit configuration as is required) would verily be amenable to be formed on the wall of the hose opposite said specific “pool” wherein it connects to a flow passage between it and the outer side of the hose, but also at the same time is characterized by the property of “self closing” from the instant the water pressure is being reduced in the hose (which is the possible solution to the suction problem and the danger of clogging following it, as we have pointed above). A design challenge that makes the situation even more stringent—achieving the “self closing” property, necessitates a relative long slit. Increasing the length of the slit compels (dictates) to increase as well the dimensions of the “pool” in the body of the discrete dripper, in a manner that on the face of it is in contradiction to the other challenge of reducing the dimensions of the dripper as we have pointed before.
Thus, as per integral dripper hoses with relatively thin walls, it is rather common, for example, to encounter the usage of flat and continuous strip drippers that—as said—enables forming sufficient long enough exit “pools” that would include within their boundaries the relatively long slit formed at the thin wall of the hose. But also, simultaneously, the flat and continuous strip embodies drawbacks—more raw material is required to produce it (in comparison to discrete drippers), and also its water pressure reducing means formed in it, does not benefit from the advantages of accuracy that the injection technology provides (as in the manufacturing of discrete drippers). For example—forming a water pressure reducing means of the labyrinth type on a flat and continuous strip is executed by the embossing technology that does not enable to achieve the same high level of accuracy in the dimensions of the minimal flow passage between the labyrinth's baffles in comparison with the (rather) substantial accuracy that might be achieved when forming the dripper by injection technology (that is executed, as said, when manufacturing a discrete dripper).
Thus, in the time that preceded the present invention, there existed a need for discrete integral flat drippers, that would be small in their dimensions and that would not require complicated adjustment and orientation operations before being affixed (attached) flush to the inner wall of the hose, enable efficient filtering of the water entering into them and providing efficient reduction of the pressure of the water while maintaining a large as possible minimal flow passage at the water pressure reduction means that is implemented for this purpose (for example—a labyrinth), that would facilitate conforming with the challenge of forming a water exit outlet in the wall of the hose, with accuracy so that it is exactly opposite the exit “pool” that is formed on them, and that would also enable using a water exit outlet endowed with “self closing” features (namely—having a water exit outlet in a thin and long slit configuration).